Undetected OB costing sheep producers

Monday 11 August

Sheep producers in South Australia should be on the look out for signs of ovine brucellosis in their flocks and make sure they manage their properties to keep the disease out.

A survey completed by PIRSA of sheep flocks in the pastoral region indicated nearly 10% of properties are infected with OB.  This was slightly lower than the 13% of flocks found to be positive in a previous survey in the Mallee region.

Trent Scholz, PIRSA Animal Health Officer said:  “We tested rams from 30 randomly selected properties and in the flocks that tested positive about 15% of the rams were infected. These properties were unaware that they had the disease.

“The cost of the disease to individual producers through lost production can be high.

“OB causes infertility in rams and can be spread from infected rams to uninfected rams and occasionally ewes.  The disease results in a lower lambing percentage, a longer lambing period and a loss of valuable ram genetics.”

Producers can minimise the risk of introducing OB by maintaining boundary fences to ensure neighbouring sheep are kept out and buy rams from OB-free accredited studs.

“The survey showed that about 30% of producers are not buying their rams from OB-free accredited studs,” he said.

“Buying rams from an accredited stud gives you peace of mind that you are not introducing the disease into the flock.

“Once a property is infected with OB the disease can be eradicated by culling all rams and replacing them with clean rams, or by carrying out a test and cull program which can be lengthy and expensive. There is no practical individual ram treatment.”

If producers notice unexplained decreases in lambing percentages, longer lambing periods, or rams with abnormal lumps in their testicles, they should consult with their local vet or PIRSA Animal Health Officer to assess the possibility of OB in their flock.

“OB is a problem that occurs in sheep flocks around SA but producers don’t realise they might have it in their flock,” he said.

PIRSA Animal Health is planning to conduct further surveys in other regions around South Australia in the coming year.